Third−Generation (3G) Wireless Systems
OVERVIEW:
Wireless continues to develop around the world.
Several different standards committees are
working on integrating wireless architecture into
the overall fold of the network.
Basically, these designations refer to different
generations of mobile telephone services, new ones which come along about every
ten years. 3G, which is the one most widely used today, is the International
Telecommunication Union (ITU) standard for third generation mobile telephone
systems under the International Mobile Telecommunications program, IMT-2000.
Analog cellular was the first generation, digital PCS was the second. Along
with W-CDMA 3G was the big rage in the
late 90's, with proponents announcing that it was the Killer Wireless
Application because of its ability to simultaneously transfer voice data (the
phone call) and other non-voice data such as music, photographs, video, email,
instant messaging, and information downloads. 3G networks use a variety of
wireless network technologies, including GSM, CDMA, TDMA, WCDMA, CDMA2000, UMTS
and EDGE, and this leads to some confusion as well as a great deal of
flexibility.
some operators will begin the next step in the
evolution process to Enhanced Data for Global Environment (EDGE). With
EDGE, existing TDMA networks can host a variety of new applications, including
·
Online e−mail
·
Access to the World Wide Web
·
Enhanced short message services
·
Wireless imaging with instant photos or
graphics
·
Video services
·
Document/information sharing
·
Surveillance
·
Voice messaging via Internet
·
Broadcasting
At
the same time, some operators will skip the step to EDGE and go directly to Universal
Mobile
Telecommunications Services (UMTSs), or what we consider to be a 3G technology.
The
steps are shown in Figure 25- 1: as the carriers choose which way to proceed.
Figure
25−2, using the
evolution of the various techniques that
emerged over the years.
GPRS:
GPRS
operates at much higher speeds than current networks, providing advantages from
a
software
perspective. Wireless middleware currently is required to enable slow speed
mobile clients to work with fast networks for applications such as e−mail,
databases, groupware, or Internet access. With GPRS, wireless middleware will
probably be unnecessary, making it easier to deploy wireless solutions.
Although current wireless applications are text oriented, GPRS' high throughput
finally makes multimedia content, including graphics, voice, and video,
practical. Imagine participating in a videoconference while waiting for your
flight at the airport, something that is completely out of the question with
today's data networks.
In
the case of VPNs, GPRS works well because of its GPRS
Tunneling Protocol (GTP) that can secure the mobile data while in
transit on the wireless networks, and IPSec transfers can be used when
transiting the wireline networks. The GTP is shown in Figure 25−3. Figure:
GTP
with VPNs
The
IP protocol is ubiquitous and familiar, but what is X.25, and why is support
for it important? X.25 defines a set of communications protocols that, prior to
the Internet, constituted the basis of the world's largest packet data
networks. These X.25 networks are still widely used, especially in Europe and
the Far East. Wireless access to these networks will benefit many
organizations. Any existing IP or X.25 application will now be able to operate
over a Global System for Mobile Communications (GSM) cellular connection. Think of cellular networks with GPRS service
as wireless extensions of the Internet and existing X.25 networks as similar to
a Local Area Network
(LAN) connection. As a LAN connection, once a GPRS mobile
station (MS) registers with the network, it is ready to
send and receive packets.
Because
there is minimal delay before sending data, GPRS is ideally suited for
applications such as:
- · Extended communications sessions
- · E−mail communications
- · Chat
- · Database queries
- · Dispatch
- · Stock updates
EDGE:
Beyond
GPRS, EDGE takes the cellular community one step closer to UMTS. It provides
higher
data
rates than GPRS and introduces a new modulation scheme called 8−Phase
Shift Keying
(PSK).
The TDMA community also adopted EDGE for their migration to UMTS. The data
rates
allocated
for EDGE are started at 384 Kbps and above as a second stage to GPRS.
The
protocol stack for EDGE is shown in Figure 25−5.
Twenty
billion SMS messages are sent worldwide every month. In Japan, there are more
than 10 million users of the iMode service — which is comparable with basic WAP
service — and each week another 150,000 new iMode users are added. In a few
years, many of us will wonder how we managed without the mobile Internet: It
will become an invaluable part of our everyday lives. Giving us more
opportunities to keep in touch with friends, family, and colleagues, empowering
us to make fast, yet well−informed business decisions, giving us instant access
to information and services and enabling us to purchase the things we need or
desire — all in a handy, pocket−sized device. We can expect to see the following
types of services from 3G products:
• Customized infotainment
• Multimedia messaging service
• Mobile intranet/extranet Access
• Mobile Internet access
• Location−based services
3G implementation was slower than
initially anticipated, however, because of the cost of upgrading equipment and
licensing fees for additional spectrum. The earlier, 2G networks didn't
typically use the same frequencies as 3G (except in the United States), and
licensing fees, particularly in Europe, were extremely expensive. Only Japan
and South Korea were able to implement this technology quickly, largely because
of the high level of government support for new infrastructure advances. In
Japan, by the end of 2006 the majority of customers were on 3G and upgrades to
the next stage, 3.5G (with 3 Mbit/s data rates), were underway. Implementation
in the rest of the world is coming along, but at a slightly slower pace. In
December 2007, 190 3G networks were operating in 40 countries, with 200 million
subscribers, and those figures have increased since then -- but there are 3
billion mobile phone subscriptions worldwide so we can expect to see different
parts of the world operating on different standards for years to come.
You may also see terms like 3.5G (or 3.75, 3.9 etc. -- almost there) and 4G (the latest and greatest on the horizon). In fact, as early as 2008 we started seeing the transition towards 4G services. The standard for 4G, however, wasn't finalized by the ITU-R until 2009, setting peak speed requirements for 4G service at 100 Mbit/s for high mobility communications (such as from trains and cars) and 1 Gbit/s for low mobility communication (e.g., stationary users and pedestrians). Not all devices and networkds marketed as 4G actually meet the requirements of the standard. On December 6, 2010, ITU declared that current versions of Long-Term-Evolution (LTE), mobile WiMax and other evolved 3G technologies that do not fulfill all the requirements of the standard can still be considered as 4G, as long as they provide clear forerunners to the full IMT-Advanced requirements and represent 'a substantial level of improvement in performance and capabilities with respect to the initial third generation systems now deployed.' As the deployment of 4G, like earlier generations, will involve the complete replacement of existing handsets and networks, it will also take many years for implementation. Candidate 4G systems replace CDMA spread spectrum radio technology used in 3G systems and IS-95 with wide channel OFDMA and Single Carrier FDMA (SC-FDE) technologies, MIMO transmission and an all-IP based architecture. There are a number of different technologies under development as well as different standards for these technologies.
For ease of reference, we've combined information on all the "Gs" on this page. The articles, resources, references and links below may help you through this maze of alphabet soup, jargon, acronyms and confusing standards!
You may also see terms like 3.5G (or 3.75, 3.9 etc. -- almost there) and 4G (the latest and greatest on the horizon). In fact, as early as 2008 we started seeing the transition towards 4G services. The standard for 4G, however, wasn't finalized by the ITU-R until 2009, setting peak speed requirements for 4G service at 100 Mbit/s for high mobility communications (such as from trains and cars) and 1 Gbit/s for low mobility communication (e.g., stationary users and pedestrians). Not all devices and networkds marketed as 4G actually meet the requirements of the standard. On December 6, 2010, ITU declared that current versions of Long-Term-Evolution (LTE), mobile WiMax and other evolved 3G technologies that do not fulfill all the requirements of the standard can still be considered as 4G, as long as they provide clear forerunners to the full IMT-Advanced requirements and represent 'a substantial level of improvement in performance and capabilities with respect to the initial third generation systems now deployed.' As the deployment of 4G, like earlier generations, will involve the complete replacement of existing handsets and networks, it will also take many years for implementation. Candidate 4G systems replace CDMA spread spectrum radio technology used in 3G systems and IS-95 with wide channel OFDMA and Single Carrier FDMA (SC-FDE) technologies, MIMO transmission and an all-IP based architecture. There are a number of different technologies under development as well as different standards for these technologies.
For ease of reference, we've combined information on all the "Gs" on this page. The articles, resources, references and links below may help you through this maze of alphabet soup, jargon, acronyms and confusing standards!
References:
Broandband Telecommunications Handbook
